Commit 0172afef authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Steven Rostedt (Google)
Browse files

tracing: Record task flag NEED_RESCHED_LAZY. 

The scheduler added NEED_RESCHED_LAZY scheduling. Record this state as
part of trace flags and expose it in the need_resched field.

Record and expose NEED_RESCHED_LAZY.

[bigeasy: Commit description, documentation bits.]

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20241122202849.7DfYpJR0@linutronix.de


Reviewed-by: default avatarAnkur Arora <ankur.a.arora@oracle.com>
Reviewed-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 06afb0f3

Documentation/trace/ftrace.rst

+4 −0
Original line number Diff line number Diff line
@@ -1033,9 +1033,13 @@ explains which is which. 
  irqs-off: 'd' interrupts are disabled. '.' otherwise.



  need-resched:

	- 'B' all, TIF_NEED_RESCHED, PREEMPT_NEED_RESCHED and TIF_RESCHED_LAZY is set,

	- 'N' both TIF_NEED_RESCHED and PREEMPT_NEED_RESCHED is set,

	- 'n' only TIF_NEED_RESCHED is set,

	- 'p' only PREEMPT_NEED_RESCHED is set,

	- 'L' both PREEMPT_NEED_RESCHED and TIF_RESCHED_LAZY is set,

	- 'b' both TIF_NEED_RESCHED and TIF_RESCHED_LAZY is set,

	- 'l' only TIF_RESCHED_LAZY is set

	- '.' otherwise.



  hardirq/softirq:

include/linux/trace_events.h

+1 −0
Original line number Diff line number Diff line
@@ -184,6 +184,7 @@ unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status); 


enum trace_flag_type {

	TRACE_FLAG_IRQS_OFF		= 0x01,

	TRACE_FLAG_NEED_RESCHED_LAZY	= 0x02,

	TRACE_FLAG_NEED_RESCHED		= 0x04,

	TRACE_FLAG_HARDIRQ		= 0x08,

	TRACE_FLAG_SOFTIRQ		= 0x10,

kernel/trace/trace.c

+2 −0
Original line number Diff line number Diff line
@@ -2552,6 +2552,8 @@ unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status) 
		trace_flags |= TRACE_FLAG_NEED_RESCHED;

	if (test_preempt_need_resched())

		trace_flags |= TRACE_FLAG_PREEMPT_RESCHED;

	if (IS_ENABLED(CONFIG_ARCH_HAS_PREEMPT_LAZY) && tif_test_bit(TIF_NEED_RESCHED_LAZY))

		trace_flags |= TRACE_FLAG_NEED_RESCHED_LAZY;

	return (trace_flags << 16) | (min_t(unsigned int, pc & 0xff, 0xf)) |

		(min_t(unsigned int, migration_disable_value(), 0xf)) << 4;

}

kernel/trace/trace_output.c

+13 −1
Original line number Diff line number Diff line
@@ -462,17 +462,29 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry) 
		bh_off ? 'b' :

		'.';



	switch (entry->flags & (TRACE_FLAG_NEED_RESCHED |

	switch (entry->flags & (TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_NEED_RESCHED_LAZY |

				TRACE_FLAG_PREEMPT_RESCHED)) {

	case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_NEED_RESCHED_LAZY | TRACE_FLAG_PREEMPT_RESCHED:

		need_resched = 'B';

		break;

	case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_PREEMPT_RESCHED:

		need_resched = 'N';

		break;

	case TRACE_FLAG_NEED_RESCHED_LAZY | TRACE_FLAG_PREEMPT_RESCHED:

		need_resched = 'L';

		break;

	case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_NEED_RESCHED_LAZY:

		need_resched = 'b';

		break;

	case TRACE_FLAG_NEED_RESCHED:

		need_resched = 'n';

		break;

	case TRACE_FLAG_PREEMPT_RESCHED:

		need_resched = 'p';

		break;

	case TRACE_FLAG_NEED_RESCHED_LAZY:

		need_resched = 'l';

		break;

	default:

		need_resched = '.';

		break;